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    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
        async function main() {
            //1. 如果返回值是一个非Promise类型的数据
            //fulfilled  521
            // return 521 ;

            // 2. 如果返回的是一个Promise对象  fulfilled  OK
            // return new Promise((resolve, reject) => {
            //     resolve('OK');

                //rejected   error 
                // reject('Error');
                // });

                //3. 抛出异常,   rejected  Oh NO
                throw "Oh NO";
            // })
        }
        let result = main();
        console.log(result);
    </script>
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